1. Field of the Invention
The present invention relates to a band coupling structure incorporating conductive wires used for portable compact information terminals that receive many kinds of information by utilizing radio waves, such as a radio controlled wristwatch, a wristwatch-type pager, a portable telephone, a portable television, and a portable radio.
2. Description of the Related Art
An electronic watch that receives standard radio waves, that is a radio watch that receives standard radio waves (carrier waves) including time information and that indicates accurate time by extracting time information from the radio waves, has already been known.
In addition, a wristwatch-type radio receiver that calls with radio or that exchanges information by receiving/transmitting electronic data has also already been known. Such a radio watch and a wristwatch-type radio receiver, in which an antenna (conductive wire) configuring a receiving section is enclosed in a main body case or a wrist band, have already been put on the market.
However, in the case in which an antenna is enclosed in a main body case made of conductive material such as metal, a magnetic flux generated around the antenna is absorbed in the conductive material and a resonance phenomenon is prevented. As a result, the receiving function of the antenna is greatly deteriorated to the degree that the antenna cannot receive the standard radio waves.
For some radio watches, a proposal has been made to prevent the receiving function of the antenna from being deteriorated even if a main body case made of conductive material is used. For some wristwatch-type radio receivers, however, an antenna may be enclosed in a wrist band to satisfy desired antenna characteristics such as a gain.
That is to say, the opening area of an antenna is enlarged to improve an antenna gain. In general, a frequency of radio waves to be received for a wristwatch-type radio receiver is higher than that for a radio controlled wristwatch. For instance, a frequency of radio waves that are used by a radio watch is in the range of 40 to 60 kHz. On the other hand, a frequency of radio waves that are used by a wristwatch-type pager, which is one of wristwatch-type radio receivers, is in the range of 100 to 300 MHz. Such difference in frequencies is related to an amount of information to be transmitted. That is to say, a transmission rate of information is made preferably higher to efficiently transmit and receive a large amount of information. Consequently, a frequency should be preferably made higher to make a transmission rate higher.
A most simple tuning means for receiving radio waves is to make the length of an antenna equivalent to wave length. Since electromagnetic waves are transmitted in a space at a speed same as that of light (300,000 km per second), wave length can be obtained by dividing a light velocity by a frequency. For instance, the length of an antenna is set to 1 m in the case in which a frequency is 300 MHz. However, it is difficult to lengthen an antenna to be 1 m for a wristwatch-type radio receiver. Therefore, in many cases, many kinds of tuning means are utilized while an antenna is made shorter than wave length. As one of such many methods, it is known that an opening area of an antenna is enlarged.
However, in the case in which an antenna that includes a large opening area is enclosed in a main body case, a main body is enlarged, resulting in the deterioration of portability, an external appearance, and attractiveness as a product. Therefore, for many products with a high frequency of radio waves to be received, an antenna is enclosed in a wrist band to make an opening area as large as possible.
Many types of wristwatch-type radio receivers provided with an antenna in a wrist band have been proposed (see the Patent Document 1, namely, Japanese Patent Laid-Open Publication No. HEI 5 (1993)-183454, for instance). The wristwatch-type radio receiver described in the Patent Document 1 has a configuration as shown in FIG. 12.
A wristwatch-type radio receiver 100 is provided with a wristwatch-type radio receiver main body 104 including a liquid crystal panel 102 that displays received messages. The bands 106 and 108 made of a nonconductive member such as leather and vinyl leather to be worn on a wrist are attached to the wristwatch-type radio receiver main body 104.
The antenna members 110 and 112 made of a thin metal plate are installed in the bands 106 and 108, respectively. The antenna members 110 and 112 are connected to a circuit of a receiving apparatus (not shown) installed in the wristwatch-type radio receiver main body 104.
A hook metal fitting 116 is attached to the free edge of the band 106, and a link metal fitting 114 is attached to the band 108 in such a manner that the link metal fitting 114 can be slid and fixed to the desired position.
By the above configuration, the wristwatch-type radio receiver can be worn on a wrist by engaging the hook metal fitting 116 of the band 106 with the link metal fitting 114 of the band 108.
On the rear surface of the band 106, a conductive projection 118 is formed at the position to which the hook metal fitting 116 is attached.
By the above configuration, in the case in which the hook metal fitting 116 of the band 106 is engaged with the link metal fitting 114 of the band 108, the projection 118 touches the antenna member 112 exposed through a hole 120 of the band 108, thus electrically connecting antenna members 110 and 112 to each other. As a result, the antenna members 110 and 112 can form a loop.
Patent Document 1: Japanese Patent Laid-Open Publication No. HEI 5 (1993)-183454 (Pages 2 and 3, and FIG. 1)
In such a configuration in which the conductive projection 118 of the band 106 touches the antenna member 112 of the band 108, a structure for fixing the bands 106 and 108 to each other are different and separate from a structure for maintaining the electrical connection of antennas. Consequently, the bands 106 and 108 cannot rotate (swing) to each other in the width direction of the bands to each other around the contact section 122 between the conductive projection 118 and the antenna member 112 as shown by the arrows A in FIG. 13.
Accordingly, in the case in which the wristwatch-type radio receiver 100 is worn on a wrist, the movement in the width direction of the bands 106 and 108 (the direction of the arrow A) has no margin as described above. As a result, it is impossible that the band position is finely adjusted in such a manner that the wristwatch-type radio receiver is suitably worn according to the size and shape of wrists depending 6n persons, thus resulting in unpleasant wear and occasionally unfitness.
In consideration of the circumstances, it is an object of the present invention to provide a band coupling structure incorporating conductive wires to be used for receiving radio waves in portable compact information terminals that receive many kinds of information by utilizing radio waves. For such a band coupling structure, the bands can rotate (swing) to each other in the width direction of the bands at a band coupling section, the movement of the bands in the width direction of the band has a margin, the band position can be finely adjusted in such a manner that the wristwatch-type radio receiver is suitably worn according to the size and shape of a worn section of a human body such as a wrist, unpleasant wear and unfitness can be prevented, a satisfactory electrical connection of conductive wires can be maintained even in the case in which the bands rotate to each other, and the bands can be easily attached to or detached from a worn section of a human body such as a wrist.